/******************************************************************
* This example will hide a prim whenever an avatar is sitting on the prim the script is in.
* Place this script into the prim you want to make invisible.
******************************************************************/

default{
    changed(integer change){
        if(change & CHANGED_LINK){
            if(llAvatarOnSitTarget() == NULL_KEY){
                llSetAlpha(1,ALL_SIDES);//visible
            }
            else{
                llSetAlpha(0,ALL_SIDES);//invisible
            }
        }
    }
}